The invention relates to a suction lifter intended for the temporary fixing on a substantially smooth, air-impermeable fixing surface, said suction lifter comprising a suction cup to be placed against a fixing surface and having a deformable suction disc, the suction lifter being designed for forming a hollow space under a partial vacuum condition between the suction disc and the fixing surface, wherein the suction disc is arranged between the suction cup and the fixing surface, wherein the suction cup further has a circumferential cup rim surrounding the hollow space, a circumferential supporting area of an upper side of the suction disc facing the cup rim being supported against the cup rim under a vacuum condition.
Suction lifters of this kind are used especially in cases where the suction lifter fixed on the fixing surface is subject to shearing forces substantially acting or acting with at least one component force parallel to the fixing surface. This particularly applies where the suction lifter is mounted on inclined or vertical fixing surfaces and is subject to forces in a direction at least substantially parallel to the fixing surface, for example when objects having vertical fixing surfaces are to be lifted using a suction lifter or when the suction lifter is mounted on a wall area in which it is used as a holding device, for example as a temporary handle for persons. Moreover, suction lifters of this kind are frequently also subject to torsion forces about the longitudinal axis of the suction lifter.
Generally the problem exists that the suction lifter, at a given size of the suction disc, shall provide a holding capacity as high as possible over a holding time as long as possible when shearing forces are applied. Although the holding capacity of a suction lifter can be increased by increasing the suction cup and the suction disc, limits are frequently set in practice, for instance due to the spatial conditions and the resulting limitations on behalf of the fixing surface, due to interruptions of the fixing surface or when the fixing surface with its mainly smooth and air-impermeable surface areas is structured, such as tiled wall areas for instance, with joints between the tiles. Generally it turned out that an increased load capacity can be achieved with an increased hardness of the suction disc, since the suction disc offers a higher resistance when it is subject to shearing forces, and this higher resistance prevents early deformation that would finally lead to a loss of the partial vacuum in the hollow space. On the other hand, the hardness of the suction disc has to be adjusted also to other demands. For instance, the fixing surface on which the suction lifter is to be fixed frequently exhibits a certain roughness or surface irregularities, e.g. also in the case of tiles, so that an excessive hardness of the suction disc would prevent the suction disc from sufficiently conforming to the fixing surface, so that the shearing forces the suction lifter is capable to resist are also limited, since leaks between the suction lifter and the fixing surface cause a loss of vacuum.